function [ status ] = mx_eyelink_data_stop( )
%MX_EYELINK_DATA_STOP Places tracker in idle (off-line) mode, does not flush 
% data from queue.
%
% Remarks:
% Should be followed by a call to eyelink_wait_for_mode_ready().
% Returns:
% 0 if command sent OK, else link error.
%
%----------------------------------------------------------------------------
% Copyright Eduardo Aponte 2013
% aponteeduardo@gmail.com